U.S. patent application number 17/387364 was filed with the patent office on 2022-02-03 for shielded electric wire and wire harness.
This patent application is currently assigned to Yazaki Corporation. The applicant listed for this patent is Yazaki Corporation. Invention is credited to Noriyuki ABE, Hiroki KONDO, Mizuki SHIRAI.
Application Number | 20220032861 17/387364 |
Document ID | / |
Family ID | 79300664 |
Filed Date | 2022-02-03 |
United States Patent
Application |
20220032861 |
Kind Code |
A1 |
SHIRAI; Mizuki ; et
al. |
February 3, 2022 |
SHIELDED ELECTRIC WIRE AND WIRE HARNESS
Abstract
A shielded electric wire includes one metal pipe and one
electric wire having a conductor and an insulator. An outer
diameter of the conductor at 25.degree. C. is set as a, a
coefficient of linear expansion of the conductor is set as
.alpha..sub.a, and a temperature difference between a maximum
temperature and 25.degree. C. is set as .DELTA.t, an outer diameter
a' of the conductor after thermal expansion is
a'=a+.alpha..sub.a.times.a.times..DELTA.t, and when a wall
thickness of the insulator at 25.degree. C. is set as b and a
coefficient of linear expansion of the insulator is set as
.alpha..sub.b, an insulator wall thickness b' after thermal
expansion is b'=b+.alpha..sub.b.times.b.times..DELTA.t, and an
inner diameter c of the one metal pipe is set to satisfy
c.gtoreq.a'+2b'.
Inventors: |
SHIRAI; Mizuki; (Susono-shi,
JP) ; KONDO; Hiroki; (Susono-shi, JP) ; ABE;
Noriyuki; (Susono-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yazaki Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Yazaki Corporation
Tokyo
JP
|
Family ID: |
79300664 |
Appl. No.: |
17/387364 |
Filed: |
July 28, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01B 7/201 20130101;
H01R 13/6592 20130101; B60R 16/0207 20130101; H02G 3/0481
20130101 |
International
Class: |
B60R 16/02 20060101
B60R016/02; H01R 13/6592 20060101 H01R013/6592; H01B 7/20 20060101
H01B007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 29, 2020 |
JP |
2020-128038 |
Claims
1. A shielded electric wire comprising: one metal pipe having a
tubular shape; and an electric wire being only one electric wire
provided in the one metal pipe, and having a conductor and an
insulator provided on an outer circumference of the conductor,
wherein when an outer diameter of the conductor at 25.degree. C. is
set as a, a coefficient of linear expansion of a conductor material
of the conductor is set as .alpha..sub.a, and a temperature
difference between a maximum temperature exposed in an environment
where the electric wire is used and 25.degree. C. is set as
.DELTA.t, an outer diameter a' of the conductor after thermal
expansion with respect to the maximum temperature is
a'=a+.alpha..sub.a.times.a.times..DELTA.t, and when a wall
thickness of the insulator at 25.degree. C. is set as b and a
coefficient of linear expansion of an insulator material of the
insulator is set as .alpha..sub.b, an insulator wall thickness b'
after thermal expansion with respect to the maximum temperature is
b'=b+.alpha..sub.b.times.b.times..DELTA.t, and an inner diameter c
of the one metal pipe is set to satisfy c.gtoreq.a'+2b'.
2. The shielded electric wire according to claim 1, wherein a
thermoplastic elastomer is filled between the one metal pipe and
the electric wire.
3. A wire harness comprising: the shielded electric wire according
to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2020-128038 filed on
Jul. 29, 2020, the contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a shielded electric wire
and a wire harness.
BACKGROUND ART
[0003] In the related art, a shielded electric wire has been
proposed in which a plurality of electric wires are collectively
put into a metal pipe to exert a shielding function and prevent
foreign matter from interfering with the electric wire (see, for
example, JP-A-2004-171952). In particular, by putting the plurality
of electric wires into the metal pipe collectively and then
connecting the metal pipe to the ground, ground connection of the
shielded electric wire can be done only once.
[0004] However, in the shielded electric wire described in
JP-A-2004-171952, a plurality of electric wires are collectively
put in a metal pipe. Therefore, a diameter of the metal pipe tends
to be large, and when the shielded electric wire is bent at the
time of wiring to a vehicle or the like, a bending radius R of the
shielded electric wire becomes large. As a result, it cannot be
said that the wiring property of the shielded electric wire is good
at all. Therefore, it is conceivable to reduce the diameter of the
metal pipe as much as possible so that, for example, a plurality of
electric wires and an inner surface of the metal pipe are brought
into close contact with each other. However, in this case, the
electric wire expands due to a temperature environment where the
shielded electric wire is used, and thus the electric wire is
crushed.
SUMMARY OF INVENTION
[0005] The present disclosure is made to solve such a problem of
the related art and an object of the present disclosure is to
provide a shielded electric wire and a wire harness which can
prevent the electric wire from being crushed while suppressing a
bending radius R and improving a wiring property.
[0006] According to an aspect of the present disclosure, there is
provided a shielded electric wire including:
[0007] one metal pipe having a tubular shape; and
[0008] an electric wire being only one electric wire provided in
the one metal pipe, and having a conductor and an insulator
provided on an outer circumference of the conductor, wherein
[0009] when an outer diameter of the conductor at 25.degree. C. is
set as a, a coefficient of linear expansion of a conductor material
of the conductor is set as .alpha..sub.a, and a temperature
difference between a maximum temperature exposed in an environment
where the electric wire is used and 25.degree. C. is set as
.DELTA.t, an outer diameter a' of the conductor after thermal
expansion with respect to the maximum temperature is
a'=a+.alpha..sub.a.times.a.times..DELTA.t, and when a wall
thickness of the insulator at 25.degree. C. is set as b and a
coefficient of linear expansion of an insulator material of the
insulator is set as .alpha..sub.b, an insulator wall thickness b'
after thermal expansion with respect to the maximum temperature is
b'=b+.alpha..sub.b.times.b.times..DELTA.t, and an inner diameter c
of the one metal pipe is set to satisfy c.gtoreq.a'+2b'.
[0010] According to the present disclosure, it is possible to
prevent the electric wire from being crushed while suppressing the
bending radius R and improving the wiring property.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a cross-sectional view illustrating an example of
a wire harness according to an embodiment of the present
disclosure.
[0012] FIG. 2 is a cross-sectional view illustrating a state when
an electric wire is thermally expanded.
[0013] FIG. 3 is a graph illustrating an example of the change of
diameter relating to linear expansion.
[0014] FIG. 4 is a cross-sectional view illustrating a shielded
electric wire according to a second embodiment.
[0015] FIG. 5 is a cross-sectional view illustrating another
example of the shielded electric wire according to the second
embodiment.
DESCRIPTION OF EMBODIMENTS
[0016] Hereinafter, the present disclosure will be described with
reference to preferred embodiments. The present disclosure is not
limited to the embodiments shown below and can be appropriately
modified without departing from the spirit of the present
disclosure. In the embodiments shown below, some parts of the
configurations are not illustrated or explained. However, it goes
without saying that, as for the details of the omitted technology,
publicly known or well-known technology is appropriately applied as
long as there is no contradiction with the contents described
below.
[0017] FIG. 1 is a cross-sectional view illustrating an example of
a wire harness according to an embodiment of the present
disclosure. As illustrated in FIG. 1, a wire harness WH includes a
shielded electric wire 1, and an example illustrated in FIG. 1
includes two (plurality) shielded electric wires 1. The wire
harness WH is not limited to the example illustrated in FIG. 1 as
long as the wire harness WH includes at least one shielded electric
wire 1 and another configuration. For example, as another
configuration, the wire harness WH may be provided with a connector
at an end portion of the shielded electric wire, or may be provided
with a braid or the like attached to, for example, a metal housing
of a vehicle body or an electronic device at the end portion.
[0018] The shielded electric wire 1 includes one metal pipe 10 and
one electric wire 20. One metal pipe 10 is a pipe member having a
tubular shape and is a tubular (for example, cylindrical) pipe
member having no notch in a longitudinal direction thereof in a
cross-sectional view.
[0019] One electric wire 20 includes a conductor 21 and an
insulator 22 provided on an outer circumference of the conductor
21. The conductor 21 is made of copper, aluminum, or an alloy
thereof. As the insulator 22, for example, Polyethylene (PE),
Polypropylene (PP), or foamed PE and PP is used.
[0020] In the present embodiment, only one electric wire 20 is
provided in one metal pipe 10. Therefore, when it is desired to
distribute a plurality of electric wires 20, the same number of
metal pipes 10 as the number of electric wires 20 are prepared and
one electric wire 20 is arranged in each metal pipe 10. Here, when
a plurality of electric wires are accommodated in one large metal
pipe, a bending radius R of the shielded electric wire 1 becomes
large. However, when one electric wire 20 is accommodated in one
metal pipe 10 and a plurality of these are prepared, the bending
radius R does not become large, and thus a wiring property can be
improved.
[0021] In the present embodiment, the metal pipe 10 and the
electric wire 20 satisfy the following relationship. FIG. 2 is a
cross-sectional view illustrating a state when the electric wire 20
is thermally expanded. As illustrated in FIG. 2, in the present
embodiment, when an outer diameter of the conductor 21 after
thermal expansion with respect to a maximum temperature exposed in
the environment is set as a' and a wall thickness of the insulator
after thermal expansion with respect to the maximum temperature is
set as b', an inner diameter c of one metal pipe 10 is set to
satisfy c.gtoreq.a'+2b'.
[0022] Here, when an outer diameter of the conductor 21 at
25.degree. C. is set as a (see FIG. 1), a coefficient of linear
expansion of a conductor material of the conductor 21 is set as
.alpha..sub.a, and a temperature difference between a maximum
temperature exposed in the environment where the electric wire 20
is disposed and 25.degree. C. is set as .DELTA.t, the outer
diameter a' of the conductor 21 after thermal expansion with
respect to the maximum temperature is set to
a'=a+.alpha..sub.a.times.a.times..DELTA.t. When a wall thickness of
the insulator at 25.degree. C. is set as b (see FIG. 1) and a
linear expansion coefficient of the insulator material of the
insulator is set as .alpha..sub.b, the insulator wall thickness b'
after thermal expansion with respect to the maximum temperature is
set to b'=b+.alpha..sub.b.times.b.times..DELTA.t.
[0023] With this configuration, even when the electric wire 20
expands to the maximum in the usage environment, the electric wire
20 does not expand beyond an inner surface of the metal pipe 10,
and thus it is possible to prevent the electric wire 20 from being
crushed by the inner surface of the metal pipe 10.
[0024] Next, an example of the shielded electric wire 1 according
to the present embodiment will be described. FIG. 3 is a graph
illustrating the example. In the example illustrated in FIG. 3, the
conductor is aluminum (coefficient of linear expansion
23.6.times.10.sup.-6/.degree. C.) and the insulator is polyethylene
(coefficient of linear expansion 3.58.times.10.sup.-4/.degree. C.).
The outer diameter of the conductor at 25.degree. C. is 5.00 mm and
the thickness (coating thickness) of the insulator is 1.10 mm. An
inner diameter of the metal pipe is set to .PHI.8.
[0025] In this case, the outer diameter of the electric wire at
30.degree. C. is 7.20 mm. Therefore, a clearance between the outer
diameter of the electric wire 20 and an inner diameter of the metal
pipe 10 is 0.8 mm. The outer diameter of the electric wire at
40.degree. C. is 7.21 mm, the outer diameter of the electric wire
at 50.degree. C. is 7.22 mm, the outer diameter of the electric
wire at 60.degree. C. is 7.23 mm, and the outer diameter of the
electric wire at 70.degree. C. is 7.24 mm.
[0026] The outer diameter of the electric wire at 80.degree. C. is
7.25 mm, the outer diameter of the electric wire at 90.degree. C.
is 7.26 mm, the outer diameter of the electric wire at 100.degree.
C. is 7.27 mm, the outer diameter of the electric wire at
110.degree. C. is 7.28 mm, and the outer diameter of the electric
wire at 120.degree. C. is 7.29 mm.
[0027] The outer diameter of the electric wire at 130.degree. C. is
7.30 mm, the outer diameter of the electric wire at 140.degree. C.
is 7.30 mm, the outer diameter of the electric wire at 150.degree.
C. is 7.31 mm, and the outer diameter of the electric wire at
160.degree. C. is 7.32 mm.
[0028] Therefore, even at the maximum temperature (160.degree. C.)
exposed in the environment where the electric wire is used, the
outer diameter of the electric wire is 7.32 mm, which does not
reach the inner diameter of the metal pipe of 8 mm. As a result, a
clearance of 0.68 mm between the outer diameter of the electric
wire 20 and the inner diameter of the metal pipe 10 is secured.
[0029] In this way, by the configurations of the shielded electric
wire 1 and the wire harness WH according to the present embodiment,
one metal pipe 10 and only one electric wire 20 provided in the one
metal pipe 10 are provided. Therefore, the bending radius R can be
suppressed by reducing the diameter of the metal pipe 10 as
compared with the case where a plurality of electric wires are
provided in the metal pipe. The inner diameter c of one metal pipe
10 satisfies c.gtoreq.a'+2b' when the outer diameter of the
conductor 21 after thermal expansion is a' and the wall thickness
of the insulator after thermal expansion is b'. Therefore, even
when one electric wire 20 thermally expands at the maximum
temperature in the usage environment, it is possible to prevent the
electric wire 20 from being crushed due to expansion exceeding the
inner diameter c of the metal pipe 10. Therefore, it is possible to
prevent the electric wire 20 from being crushed while suppressing
the bending radius R and improving the wiring property.
[0030] Next, a shielded electric wire according to a second
embodiment of the present disclosure will be described. The
shielded electric wire according to the second embodiment is the
same as that of the first embodiment, but the configuration is
partially different. Hereinafter, differences from the first
embodiment will be described.
[0031] FIG. 4 is a cross-sectional view illustrating the shielded
electric wire 2 according to the second embodiment. As illustrated
in FIG. 4, in a shielded electric wire 2 according to the second
embodiment, a thermoplastic elastomer 30 is interposed between one
metal pipe 10 and one electric wire 20.
[0032] The thermoplastic elastomer 30 is composed of, for example,
any one of styrene-based thermoplastic elastomers (SBC and TPS),
polyolefin-based elastomer (TPO), polyester-based elastomer (TPEE
and TPC), vinyl chloride-based elastomer (TPVC), polyurethane-based
elastomers (TPU), and the like, or a combination thereof.
[0033] Such the thermoplastic elastomer 30 is softer than the
insulator 22 at room temperature (around 25.degree. C.) or the like
and does not hinder the expansion of the electric wire 20 during
the thermal expansion of the electric wire 20. In particular, the
thermoplastic elastomer 30 softens more in a high temperature
environment, so that it becomes difficult to inhibit the expansion
of the electric wire 20. A part of the thermoplastic elastomer 30
protrudes from both ends of the metal pipe 10, for example, due to
the expansion of the electric wire 20, but the protruded part of
thermoplastic elastomer 30 returns to its original position when
the electric wire 20 cools down.
[0034] FIG. 5 is a cross-sectional view illustrating another
example of the shielded electric wire 2 according to the second
embodiment. It is assumed that the shielded electric wire 2
according to the second embodiment is bent at the time of wiring to
a vehicle or the like. In this case, as illustrated in FIG. 5, the
metal pipe 10 has a slightly flat shape, but the thermoplastic
elastomer 30 follows the shape, and thus a shape of the
thermoplastic elastomer 30 changes while being interposed between
the metal pipe 10 and the electric wire 20.
[0035] The shielded electric wire 2 according to the second
embodiment may be manufactured, for example, by extruding the
thermoplastic elastomer 30 onto the electric wire 20 and then
passing the extruded thermoplastic elastomer 30 through the metal
pipe 10. The thermoplastic elastomer 30 may be extruded onto the
electric wire 20 and then formed into a tubular shape by forming a
metal plate on the thermoplastic elastomer 30. In this case, a lap
portion of the metal plate may be joined by plasma welding,
friction stir welding, or the like.
[0036] In this way, by the configuration of the shielded electric
wire 2 and the wire harness WH according to the second embodiment,
similar to the first embodiment, it is possible to prevent the
electric wire 20 from being crushed while suppressing the bending
radius R and improving the wiring property.
[0037] Further, according to the second embodiment, since the
thermoplastic elastomer 30 is filled between the metal pipe 10 and
the electric wire 20, the heat of the electric wire 20 can be
released from the metal pipe 10 through the thermoplastic elastomer
30, and thus the heat dissipation can be improved. As a result, the
expansion of the electric wire 20 itself can be suppressed and the
possibility that the electric wire 20 is crushed can be further
reduced.
[0038] Hereinbefore, the present disclosure is described based on
the embodiments. However, the present disclosure is not limited to
the embodiments described above. Changes may be made without
departing from the spirit of the present disclosure and the
techniques of the embodiments may be combined if possible, and
publicly known and well-known techniques may be combined as
appropriate.
[0039] For example, the materials and the like shown in the
embodiments described above can be changed as appropriate.
Although, in the shielded electric wire 2 according to the second
embodiment, it is assumed that the thermoplastic elastomer 30 is
provided in the entire shielded electric wire 2 in the longitudinal
direction, the present disclosure is not limited to this and the
thermoplastic elastomer 30 may be provided intermittently or
partially.
[0040] Here, the details of the above embodiments are summarized as
follows.
[0041] There is provided a shielded electric wire including: one
metal pipe having a tubular shape, and an electric wire being only
one electric wire provided in the one metal pipe, and having a
conductor and an insulator provided on an outer circumference of
the conductor, in which when an outer diameter of the conductor at
25.degree. C. is set as a, a coefficient of linear expansion of a
conductor material of the conductor is set as .alpha..sub.a, and a
temperature difference between a maximum temperature exposed in an
environment where the electric wire is used and 25.degree. C. is
set as .DELTA.t, an outer diameter a' of the conductor after
thermal expansion with respect to the maximum temperature is
a'=a+.alpha..sub.a.times.a.times..DELTA.t, and when a wall
thickness of the insulator at 25.degree. C. is set as b and a
coefficient of linear expansion of an insulator material of the
insulator is set as .alpha..sub.b, an insulator wall thickness b'
after thermal expansion with respect to the maximum temperature is
b'=b+.alpha..sub.b.times.b.times..DELTA.t, and an inner diameter c
of the one metal pipe is set to satisfy c.gtoreq.a'+2b'.
[0042] For example, a thermoplastic elastomer is filled between the
one metal pipe and the electric wire.
[0043] Here, there is also provided a wire harness including the
shielded electric wire according to the above.
* * * * *